Semiconductor devices, such as transistors, have reached well into the sub-micron range, e.g., below 0.25 microns. The semiconductor manufacturing industry has made continued advances in overall device speed and performance, while continually shrinking device size and increasing component density.
Creating strain in channel regions of planar MOS transistors may increase the mobility of charge carriers in the channel region. So-called “strain engineering” seeks to take advantage of this principle to increase the switching speed of the transistors. In general, tensile strain increases the mobility of electrons, while compressive strain increases the mobility of holes.